1. Field of the Invention
The invention relates to the field of magnetic recording and to apparatus for testing and adjusting magnetic recording devices. The invention finds particular application in the field of digital magnetic recording as practiced upon flexible disks, data cartridges, and the like.
2. Description of the Prior Art
Within the magnetic recording technology, the art can be conceptually viewed in two broad categories: (1) the magnetic recording media, and (2) the apparatus adapted to receive the magnetic recording media in order to record information thereon and/or extract information therefrom (i.e. the drive). The manufacture of magnetic recording media is an extremely delicate and subtle process which yields a family of devices among which are flexible disks, tapes, tape cassettes, data recording cartridges, and others. These magnetic media devices and/or implementations are adapted to be received by suitably designed drives. In addition, the manufacture and design of magnetic recording drives is a demanding technical achievement. Universally, the way that magnetic recording media and magnetic recording drives are tested is by operating each within a proper operating environment, i.e., placing the media to be tested within a "standard" drive or placing a "standard" media device within a drive to be tested.
Both the testing of drives using "standard" media and the testing of media using "standard" drives are frought with difficulties. First, the actual error rate of a magnetic recording device when reading and writing is a complex function of many variables including the media/drive interface. Head/media separation bears an exponential relationship to read back amplitude, and, thus, variations in head/media separation have geometric effect upon error rate. Second, media which might be considered "standard" today tends to degrade in time because most media is sensitive to variations in temperature, humidity, handling, etc. Thus, it is desirable to have an apparatus and/or technique for separating the performance of the drive from the actual performance of the media so that magnetic recording drives can be checked and/or measured from known and verifiable standards which are unchanging.
Attempts have been made to decouple media effects from drive effects in magnetic recording. For example, attempts have been made to couple a signal into a magnetic recording drive after the read/write recording head. Though this technique is successful, it cannot be used to evaluate the performance of the head itself because the signals are coupled after the head into the read/write train. Also, this technique is cumbersome and difficult to use because in typical magnetic recording drives, access to the read/write recording head is not readily available. At the present time, no viable technique exists for test and adjustment of magnetic recording drives other than utilizing standard media for this purpose.